title: The effect of nitrous oxide on the minimum alveolar concentration (MAC) and MAC derivatives of isoflurane in dogs.
abstract: This study investigated the effects of 70% nitrous oxide (N2O) on the minimum alveolar concentration (MAC) of isoflurane (ISO) that prevents purposeful movement, the MAC of ISO at which there is no motor movement (MACNM), and the MAC of ISO at which autonomic responses are blocked (MACBAR) in dogs. Six adult, healthy, mixed-breed, intact male dogs were anesthetized with ISO delivered via mask. Baseline MAC, MACNM, and MACBAR of ISO were determined for each dog using a supra-maximal electrical stimulus (50 V, 50 Hz, 10 ms). Nitrous oxide (70%) was then administered and MAC and its derivatives (N2O-MAC, N2O-MACNM, and N2O-MACBAR) were determined using the same methodology. The values for baseline MAC, MACNM, and MACBAR were 1.39 ± 0.14, 1.59 ± 0.10, and 1.72 ± 0.16, respectively. The addition of 70% N2O decreased MAC, MACNM, and MACBAR by 32%, 15%, and 25%, respectively.
authors.affiliation: California Animal Rehabilitation, Santa Monica, California, USA (Voulgaris); Department of Small Animal Clinical Sciences (Egger), Department of Large Animal Clinical Sciences (Seddighi, Doherty), and Department of Biomedical and Diagnostic Sciences (Rohrbach), University of Tennessee, Knoxville, Tennessee, USA; Animal Emergency and Referral Associates, Fairfield, New Jersey, USA (Love).
authors.forename: Debra A
authors.initials: DA
authors.lastname: Voulgaris
authors.forename: Christine M
authors.initials: CM
authors.lastname: Egger
authors.forename: M Reza
authors.initials: MR
authors.lastname: Seddighi
authors.forename: Barton W
authors.initials: BW
authors.lastname: Rohrbach
authors.forename: Lydia C
authors.initials: LC
authors.lastname: Love
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Doherty
mesh_terms: D000768:Anesthesia, General / Q000662:veterinary; D000769:Anesthesia, Inhalation / Q000662:veterinary; D018685:Anesthetics, Inhalation / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D004285:Dogs; D007530:Isoflurane / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D009609:Nitrous Oxide / Q000494:pharmacology*; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000378:metabolism
chemical_list: D018685:Anesthetics, Inhalation; D007530:Isoflurane; D009609:Nitrous Oxide